public class Solution {

    public boolean isPalindrome(String s) {
        
        int left = 0;
        int right = s.length() - 1;
        
        while(left < right) {
            
            while(!Character.isLetterOrDigit(s.charAt(left)) && left < right) left++;
            while(!Character.isLetterOrDigit(s.charAt(right)) && right > left) right--;
            
            if(Character.toLowerCase(s.charAt(left)) != Character.toLowerCase(s.charAt(right))) return false;
            
            left++;
            right--;
            
        }
        
        return true;
        
    }
    
}